package com.zx.blog.util;


import org.commonmark.Extension;
import org.commonmark.ext.gfm.tables.TableBlock;
import org.commonmark.ext.gfm.tables.TablesExtension;
import org.commonmark.ext.heading.anchor.HeadingAnchorExtension;
import org.commonmark.node.Link;
import org.commonmark.node.Node;
import org.commonmark.parser.Parser;
import org.commonmark.renderer.html.AttributeProvider;
import org.commonmark.renderer.html.AttributeProviderContext;
import org.commonmark.renderer.html.AttributeProviderFactory;
import org.commonmark.renderer.html.HtmlRenderer;

import java.util.*;

/**
 * @author zouxu
 * @date 2020/3/26 19:25
 */
public class MarkDownUtil {
	/**
	 * markdown格式转换成HTML格式
	 * @param markdown
	 * @return
	 */
	public static String markdownToHtml(String markdown) {
		Parser parser = Parser.builder().build();
		Node document = parser.parse(markdown);
		HtmlRenderer renderer = HtmlRenderer.builder().build();
		return renderer.render(document);
	}

	/**
	 * 增加扩展[标题锚点，表格生成]
	 * Markdown转换成HTML
	 * @param markdown
	 * @return
	 */
	public static String markdownToHtmlExtensions(String markdown) {
		//h标题生成id
		Set<Extension> headingAnchorExtensions = Collections.singleton(HeadingAnchorExtension.create());
		//转换table的HTML
		List<Extension> tableExtension = Arrays.asList(TablesExtension.create());
		Parser parser = Parser.builder()
				.extensions(tableExtension)
				.build();
		Node document = parser.parse(markdown);
		HtmlRenderer renderer = HtmlRenderer.builder()
				.extensions(headingAnchorExtensions)
				.extensions(tableExtension)
				.attributeProviderFactory(new AttributeProviderFactory() {
					@Override
					public AttributeProvider create(AttributeProviderContext context) {
						return new CustomAttributeProvider();
					}
				})
				.build();
		return renderer.render(document);
	}

	/**
	 * 处理标签的属性
	 */
	static class CustomAttributeProvider implements AttributeProvider {
		@Override
		public void setAttributes(Node node, String tagName, Map<String, String> attributes) {
			//改变a标签的target属性为_blank
			if (node instanceof Link) {
				attributes.put("target", "_blank");
			}

		}
	}
}
